Why Your App Needs In-App Calling (And Why Building It Yourself Is Harder Than You Think)

A product manager’s perspective on one of the most underrated growth levers for consumer apps

Every product team I’ve talked to has a similar story. They invest heavily in onboarding, retention campaigns, push notifications — all the usual growth levers. But there’s one feature that consistently gets deprioritized despite its impact: real-time voice and video calling inside the app.

I’m Deokbeom Jeong, PM at LINE Planet — a CPaaS built on the VoIP infrastructure that powers LINE Messenger’s calls for hundreds of millions of users. In this post, I want to make the case for why in-app calling deserves a spot on your product roadmap, and what you need to think about before building it.

Why “calls” in the first place?

Text-based communication — chat, comments, DMs — is asynchronous by nature. Even the fastest messengers create a subtle disconnect: you’re never quite sure if the other person is fully present with you.

Voice and video calls change that entirely. When users talk directly, they focus, they immerse, and they engage more deeply. That’s not just intuition — it’s reflected in session length, retention, and trust metrics across consumer apps.

Audio and video calls convey emotional nuance through tone of voice and facial expressions in real-time. Text simply can’t replicate that. And for services where relationship quality matters — social apps, professional platforms, marketplaces — this gap in engagement becomes a real competitive disadvantage over time.

Why it needs to be in-app

This is the part most product teams underestimate. “Our users can just call each other on their phones” is a reasonable-sounding argument — until you think through the consequences.

1. Privacy concerns are a real user churn driver

If users need to share phone numbers to call each other, you have a privacy problem. According to a 2020 Cisco report, about 1 in 3 consumers have stopped using a service due to privacy concerns, and over 80% are highly sensitive to how their data is handled.

Some services use temporary “safety numbers” as a workaround — but this creates a different problem. Users have to leave your app to make the call. Once they’re out of your ecosystem, they may not come back.

In-app calls solve both problems at once: no personal numbers exposed, and users stay inside your product.

2. Dispute resolution becomes manageable

When users gather, disputes happen. In a text-based environment, you can review reported messages. But voice calls? Without in-app calling infrastructure, you have no visibility.

With in-app calls, you can enable call recording on a per-call basis. Those recordings become critical evidence in dispute resolution — especially important for high-value item marketplaces or platforms connecting professionals with clients.

There’s also a behavioral side effect: simply informing users that calls may be recorded tends to make them communicate more carefully. Disputes decrease before they even start.

3. AI opens up entirely new use cases

We’re at a point where combining AI with in-app voice isn’t a gimmick — it’s a legitimate product direction.

Voice AI agents are replacing text-based chatbots for customer support, and for good reason. According to HubSpot research, 69% of consumers find real-time voice support more satisfying than text — especially for complex or emotionally charged issues.

If your app already has a user communication layer, layering AI-powered voice experiences on top creates a genuinely fresh engagement moment. It can re-activate churned users and differentiate you from competitors still relying on chat-only support.

4. It can be a revenue model, not just a cost center

In-app calling doesn’t have to be purely a retention tool. Consider:

• Freemium gating: free calls up to X minutes, paid tier for unlimited
• Professional consultation platforms: experts charge per call session, with the platform taking a cut
• Marketplace trust features: verified call history as a premium seller feature

If your users are already conducting consultations or high-stakes conversations — and they’re doing it outside your app — you’re leaving both revenue and data on the table.

Build or buy?

At this point, the case for in-app calling is probably clear. The harder question is: do you build it yourself or use an existing platform?

Here’s what most teams underestimate about building from scratch:

Voice and video calling is a completely different technology stack from standard web or mobile development. You need to handle:

• Real-time media processing
• Network traversal across unpredictable conditions (WiFi, LTE, 5G, low-bandwidth)
• Global infrastructure to minimize latency across regions
• End-to-end encryption
• Continuous maintenance as network environments evolve

Getting all of this right — and keeping it right at scale — requires specialized VoIP engineers and significant infrastructure investment. Most product teams don’t have this as a core competency, and they shouldn’t need to.

That’s the problem LINE Planet was built to solve. It packages the VoIP technology and operational know-how from LINE Messenger’s calling infrastructure (running since 2011) into an SDK that developers can integrate without building the underlying stack themselves.

The bottom line

In-app calling isn’t just a “nice to have” feature. For the right products — social apps, marketplaces, professional platforms, O2O services — it’s a meaningful lever for engagement, trust, retention, and revenue.

The key questions are:

1. Is your users’ core activity something that benefits from real-time, synchronous communication?
2. Are there privacy or trust dynamics in your product where controlling the communication channel matters?
3. Could AI-powered voice change how your users interact with your product or support team?

If any of these are yes, it’s worth exploring seriously.

If you want to discuss what this could look like for your service, feel free to reach out: dl_planet_help@linecorp.com

Or try LINE Planet’s demo directly: **line-planet-call.lineplanet.me**

Originally published at docs.lineplanet.me